1. Field of the Invention
The present invention relates to a water-soluble addition polymer and particularly a water-soluble urethane polymer, and an aqueous ink using this polymer as a dispersant for a disperse dye.
The present invention also relates to an ink jet recording process and an ink jet textile printing process using this aqueous ink.
2. Related Background Art
Processes for producing aqueous polyurethanes and applications of these polymer in ink have been known. For example, (1) Japanese Patent Publication No. 63-14723 discloses an aqueous dispersion of a urethane-modified vinyl polymer and a method for making the same, (2) Japanese Patent Laid-Open No. 7-268055 discloses an aqueous polyurethane polyurea dispersion, (3) Japanese Patent Laid-Open N. 8-27242 discloses an aqueous polyurethane resin and (4) Japanese Patent Laid-Open No. 63-37160 discloses a method for producing a pigment ink using an aqueous polyurethane dispersion.
In these prior art technologies, polyurethanes are used as a dispersant for pigment in the form of an aqueous dispersion in which polyurethane particles are suspended in water, not in the form of an aqueous solution.
On the other hand, non-plate printing using ink jet recording processes has been proposed. As basic requirements in these ink jet recording processes, the dispersion must consist of fine particles having an average size of not greater than 250 nm, have a low viscosity of not greater than 3 mPa.S when containing solid components of approximately 10%, and be stable.
Technologies for dispersing disperse dyes into aqueous media have been known. Typical examples of aqueous dispersants for disperse dyes include napththalenesulfonic acid-formaldehyde condensation products and lignin sulfonate. Also, surfactants as dispersants are disclosed by, for example, Hoechst AG in Japanese Patent Laid-Open No. 48-14888, Nikka Chemical Co., Ltd. in Japanese Patent Laid-Open No. 50-100386, Toho Chemical Industry Co., Ltd. in Japanese Patent Laid-Open No. 54-2484 and ICI Inc. in Japanese Patent Laid-Open No. 55-54353. These materials are used for dispersion in conventional dyeing processes. Fine particle dispersions having an average size of not greater than 250 nm cannot, however, be produced from these materials with great efficiency and stability.
Technologies for dispersing pigment in aqueous media have been used practically in writing inks, ink jet recording inks, liquid developers for photoresists and electrophotographs. Even if these technologies are applied to dispersion of disperse dyes, the dyes are barely dispersed into fine particles of submicron regions.
Significantly stable dispersions nowadays are produced by aqueous pigment dispersing processes with aqueous dispersants. Images formed by printing or coating with inks or paints including these dispersants have high water-proof characteristics and high abrasion resistance, probably due to tight absorption, as a protective colloid, of the dispersants onto the pigment particles. The absorbed materials cannot therefore be readily desorbed from the particles by chemical or physical treatment. This phenomenon is a hindrance in the removal of dispersants after dyeing processes. Further, it is important that the fine particle dispersions be stable in cloth-dyeing processes. Production of stable dispersions with high yield from the above-mentioned conventional materials, however, is extremely difficult.